Device for closing a bore hole



1968 A. e. THUNELL ETAL 3,366,056

DEVICE FOR CLOS ING A BORE HOLE Filed March 23, 1966 INVENTOR An ers a ogT g 6 United States Patent 3,366,056 DEVICE FOR CLOSING A BORE HOLE Anders G. Thunell, Dalagatan 23, 3 tr., Stockholm, Sweden, and Rune Ek, Tollidsvagen 4B, Nacka, Sweden Filed lWar. 23, 1966, Ser. No. 536,923 7 Claims. (Cl. 102-30) ABSTRACT OF THE DISCLOSURE A bore hole closing device for insertion in a bore hole in which an explosive charge is to be placed, the plug consisting of a thin-walled tube of plastic in substantially frusto-conical shape. When inserted in the hole, a portion of the tube projects from the hole and the projecting end is provided with an identifying closure cap. The projecting end of the tube is of larger diameter than the diameter of the hole so that a wedging fit of the tube in the hole is secured. The opposite end of the tube is of smaller diameter than the diameter of the hole and the internal diameter of the tube, from one of its ends to the other end, is larger than the size of the explosive charge so that the charge can enter the hole through the tube while the tube is in place in the hole, and the tube has sufiicient flexibility in its side Wall to enable it to conform to the shape of a non-round hole when the tube is inserted in such a hole.

The present invention relates to a device for temporarily closing a bore hole in rock, in packed sand or the like, and more particularly to a kind of device in the form of a pin or peg having a shape of a frustum of a cone provided with an upper end of larger diameter somewhat greater than the diameter of the bore hole into which it is adapted to be inserted.

Previously known devices of this kind usually consist in one embodiment, of a wooden frusto-conical member of such a dimension as compared to the diameter of the bore hole, that the cone can be inserted into the bore hole to only a small extent. A cone of this character is placed into the bore hole in order to eliminate the risk of pebbles falling down into the hole or the possibility that the bore hole will be filled with water. By the insertion of a dynamite charge or blasting cartridge it is necessary to withdraw the device, which is intended as a protection. Therefore during the loading the risk of pebbles falling down into the hole increases.

The present invention solves this problem and it contemplates the p-rovision of a hollow pin or rod, which is of frusto-conical form and fits snugly into the blast hole, leaving a substantial, easily recognized portion projecting out of the top of the hole. The pin or red is of relatively thin-walled construction and while it conforms its shape under general conditions, it is capable of adapting itself closely to the interior of the hole when the hole is non-round in form.

With the above-expressed objects in view, we have devised the arrangement of parts to be described and more particularly pointed out in the claims appended hereto.

The invention will be described with reference to the attached drawing, in which the figure shown discloses a device made in accordance with the invention and fitted in a bore hole.

The bore hole 1 is, in a known manner, made by a suitable boring device in bedrock 2 or in solidly packed sand. The device 3, constructed according to the invention, is in the form of a hollow, thin-walled frusto-conical pin or rod and is provided with an upper larger-diameter end 4, the same having a diameter somewhat greater than the diameter of the bore hole 1, and having a lower end of a smaller diameter and which is less than the diameter of the bore hole 1. The diameter of the lower end is 3,36%,fi56 Patented Jan. 30, 1968 greater than the diameter of a dynamite charge or blasting cartridge which is inserted into the bore hole 1.

The top angle of the device or cone depends materially upon the flexibility of the material of which it is made and which is preferably a plastic material. The top angle, as it is known in geometry, is that angle in the plane pro jection of said cone measured between the sides of the isosceles triangle at the intersection of said sides at the point of the cone projection. It is suggested that the angle be between 3.0 and 5.5 in order to achieve a satisfactory fitting of the device in the bore hole. In the example shown, the top angle is 3.7 The length of the hole cone or pin can be 200 mm., but this can vary depending on different conditions. However, it is suitable that the top angle is so chosen that the periphery 6 of the hole 1, when the device is pressed down into the hole 1, is located at about the middle of the hole cone or pin.

The thickness of the device also depends upon the flexibility of the material of which it is composed and a suggested thickness can be about 0.51.5 mm. It is important that the thickness and top angle have such a corresponding relation, with a predetermined and suitable plastic material, that the cone or pin, through conformatory alteration in shape when it is placed into the bore hole 1, causes an almost tight fit toward the upper periphery 6 of the hole, even if this periphery has a shape of non-round conformation. The plastic material used for the cone or pin, may be of such a character that it essentially maintains its stiffness irrespective of alteration in meteorological conditions for example, such as changes in temperature.

The cone or pin is furnished with a cover, cap or lid 7, which covers and surrounds the upper larger diameter 4, so that water such as rain is prevented from entering into the bore hole 1. The lid or cover 7 only, or both the lid and the cone or pin can be given a color by adding coloring pigment into the plastic material and in which case, the cone or pin or a part thereof will be rendered easily visible to the eye. The lid 7 and the cone or pin can also be manufactured in different colors.

It is, under certain conditions, permissible and even possible, to arrange for a molecular connection between the lid 7 and the cone or pin. The device according to the invention can be of standard dimensions such as 25 and 40 mm. or other dimensions according to the sizes of the bore holes. The dimension is not limited to specific dimensions, but can vary as above described.

It will be apparent from the foregoing, that the device may be easily fitted in place to close a bore hole and when in place it will indicate its presence by its projecting and color-designated upper end. When fitted in the hole it prevents the hole from being filled with pebbles, sand or water. It fits snugly in the hole; is not readily displaced despite the fact that the hole might be more or less nonround in form. Since the pin or cone is hollow the charge of dynamite or explosive can be entered down though it into the hole by the removal of the cap 7.

Having thus described a single embodiment of the invention, it is obvious that the same is not to be restricted thereto, but is broad enough to cover all structures coming within the scope of the annexed claims.

What is claimed is:

1. A bore hole closing device comprising a hollow, flexible, thin-walled tubular means for use in a bore hole passage before and during the insertion of an explosive charge into said passage, said means being in the form of a frustrum of a cone having a top angle of an effective size to achieve a satisfactory fitting of the device intermediate the ends thereof at the upper periphery of the said bore hole, the wall of said tubular means having a thickness dimensioned to provide flexibility to adapt itself closely to the interior shape of the said bore hole, the smallest diameterof said hollow tubular means being of suflicient size to enable the insertion of said explosive charge.

2. A bore hole closing device according to claim 1, characterized in that a cover is placed on the upper largerdiameter end of the tubular means projecting above the upper periphery of the said bore hole.

3. A bore hole closing device according to claim 2, characterized in that the cover is secured to the cone by a molecular connection.

4. A bore hole closing device according to claim 1, characterized in that the said device is composed of a plastic material.

5. A bore hole closing device according to claim 1, characterized in that the top angle is in a range of about 3.0" to 5.5

6. A bore hole closing device according to claim 1, characterized in that the thickness of the Wall is dimensioned in a range of about 0.5 mm. to 1.5 mm.

7. A bore hole closing device comprising a hollow, flexible, thin-Walled tubular means for use in a bore hole passage before and during the insertion of an explosive charge into said passage, said means being in the form of a frustrum of a cone having a top angle in a range of about 30 to 5.5 to achieve a satisfactory fitting of the device intermediate the ends thereof at the upper periphery of the said bore hole, the Wall of said tubular means having a thickness dimensioned in a range of about 0.5 mm. to 1.5 mm. to provide flexibility to adapt itself closely to the interior shape of the said bore hole, the smallest diameter of said hollow tubular means being of sufficient size to enable the insertion of said explosive charge.

References Cited UNITED STATES PATENTS 1,642,118 9/1927 Lindner 102-30 1,787,910 1/1931 Lanier 10226 2,403,386 7/ 1946 Lubelsky et a1 10230 FOREIGN PATENTS 1,132,007 10/1956 France.

BENJAMIN A. BORCHELT, Primary Examiner.

V. R. PENDEGRASS, Assistant Examiner. 

